Controlling or tripping apparatus for alternating-current electric circuits



Apnl 24, 1928. 1,667,655

H. W. CLOTHIER ET AL CONTROLLING OR TRIPPING APPARATUS FOR ALTERNATING CURRENT ELECTRIC CIRCUITS Filed Sept. 17, 1925 fare/775K Wad? m Patented Apr. 24, 1928.

UNITED STATES HENRY WILLIAM CLOTHIER, OF

AIN.

CONTROLLING OR DRIPPING- APPARATUS FOR 1,667,655 PATENT OFFICE.

\VALLSEND-ONTYNE, AND \VILLIAM ANTHONY AM- BROSE BURGESS, OF MONKSEATON, ENGLAND, ASSIGNORS TO. A. PANY LIMITED, 0F HEBBURN-ON-TYNE, ENGLAND,

REYROLLE &: COM- A COMPANY 0F GREAT BRIT- ALTERNATING-CURRENT ELECTRIC CIRCUITS.

Application filed September 17, 1925, Serial No. 5?,014,

This invention relates to a protective ar rangement for use in conjunction with a trailing or like cable between an electromagnetically-opera-ted switch and electrical apparatus such as portable electric apparatus for use in say a mine for coal-cutting.

There are various known forms of relays or like devices having auxiliary windings which modify or control the operation of the relay according to the condition of the circuit containing the auxiliary winding, but the persent invention is concerned solely with the use of devices of this general type as part of a protective arrangement for an alternating current electric circuit contain ing a trailing or like cable provided with an earthed pilot circuit between an electromagnetically-operated switch and electrical apparatus. It is generally known to be desirable to provide in conjunction with the trailing cable some means whereby the gate end or like switch is opened, or it open cannotvbe closed, it the earthed' pilot circuit is incomplete.

According to the present invention there is employed, in combination with the earthed pilot circuit of the cable, an electromagnetic tripping device or relay for the switch hav ing a magnetizing or operating winding and also having an auxiliary winding in circuit with the pilot circuit, such auxiliary wind ing being normally short-circuited by the pilot circuit so that when thus short-circuited the flux due to the magnetizing winding is modified so that the tripping device does not operate. The auxiliary winding may be on the magnetic core of a relay, the magnetizing winding of which is energized from the supply mains so that the relay tends to attract an armature controlling the tripping circuitof the gate end switch. The auxiliary winding forms part of the earthed pilot circuit and when that circuit is closed the current induced by the magnetizing Winding in the auxiliary winding weakens the magnetic flux due to the magnetizing winding to suchan extent that the arm-m ture of the relay will not be attracted and thus the tripping circuit for the gate end switch will not be closed.

Again, the auxiliary winding forming part of the earthed pilot circuit may be on and in Great Britain October 3, 1924.

a limb or portion of the magnetic core of the relay which allords a shunt or alternative path for the flux, the auxiliary winding being so arranged that when its circuit is closed the cii'ect is to reduce the flux in the shuntpalh and thus cause a relative increase of flux through the main magnetic circuit and attract the armature of the relay. In this case the opening of the earthed pilot circuit containing the auxiliary winding will allow the flux due to the magnetizing winding to pass through the shunt path and consequently weaken the flux through the main pathso that the armature controlling the tripping circuit will not be attract cd or will cease tobe' attracted.

Again, the auxiliary winding may be on the magnetic core of a transformer turnished with a primary winding energized from the supply mains and having a sec ondary winding which controls the tripping circuit. In such a case the effect of the auxiliary winding which as before forms part of the earthed pilot circuit, will be to control or modify the effect of the primary winding upon the secondary winding and thus to cause the operation of the tripping circuit under the appropriate conditions.

In one application of the invention the auxiliary winding is upon the core of an eartli-leakage or core-lmlance transformer through which the three phase conductors pass. This core has a primary winding connected say between two of the phases and a secondary winding in circuit with the operating coil of an earth-leakage relay controlling a. tripping circuit.

The auxiliary winding is in circuit with the earthed pilot circuit as before and when that circuitis closed, i. e. in the normal op erating condition, the flux due to the primary winding is ractically neutralized by the closed auxiliary winding and the secondary winding thus does not operate the relay. The opei'iing of the earthed pilot circuit allows the flux due to the primary winding to have full effect upon the secondary winding and the relay consequently operates.

In the accompanying drawings,

Figures 1 and 2 are diagrams merely in dicatmg two known alternative forms of circuit-controlling or tripping devices such as may be used according .to this invention,

and

Figure 3 shows the circuit-controlling or tripping device in the form of a. transformer anlcl'used accordingto this invention in conjunction with a three-phase cable with an earthed pilot circuit and a gate end switch. YVit-h .referenc-efirst to Figure l, is the magnetic core of a relay having an operating v winding B forming part of a circuit B which according to this invention would he connected to the supply mains and when energized would cause .the armature A to -l' e;a1ttracte(jl and complete a tripping circuit Such circuit n'right tor "instance be simiiaiuto'the circuit Jil of Figure 3. The am;- iliary winding is shown :at IDv in Figure 1 and it form-s part of .a icircuitrl.) which would :be joinedto or form :part of the earthed pilot circuit such as is shown .at K in Fig .u-l-e 3. Thus it the earthed pilot circuit were not complete theauxiliary:winding' D would be open-circuited and the operating winding 15 would cause thearmature A to be picked up. thus closing .the tripping circuit. If on the other hand the .earthed pilot circuit were co-n'ip'lete, :theauxi'liary winding D would be closed and would then tendnto weaken the :fiux due to the operating winding B to such an extent that the armature A would not 'ze litted and :thus thetripping circuit would not be .closed.

The device shown inl igur '2 is intended to be connected in the various circu its and to operate in a way generally-sin a r to that described with reference to Figure 1, but in this form the .coreflil' is provided with a magnetic shunt path A round whiclrthe auxiliary wind-ing- D is wound. In this construction when the circuit ill of the auxiliary-winding D is conr 'ileted :hy the closing e t the cart hed pilot circuit, the cur-sent induced in the auxiliary winding B may be arranged to oppose or weaken the flux in the shunt path. A and thus increase the flux from the poles of the core A through the armature A". Thisarmature may be assumed in suchcircumstances to rise-and open the tripping circuit C. This form of construction may also be used with the known mechanical forms of low volt trip-ping de- Vices in which the tripping lever is mechanically'con-nec-ted to the armature.

In- Figure 3 thecircuit-controlling or tripping device has the for-m of an earth-leakage or core-balance transformer: having :a core E acted upon in a well known way by each of the conductors F, F F -oit'a three- .phase supply cable. G is a gate end switch and a trailing cable having three conductors G G G leads to some apparatus, for in stance amotor (not shown) at the other end.

The transformer has a primary Winding E connected between the two phase conductors .F and F and a secondary winding"E in circuit with a relay'H controlling a tripping circuit comprising a battery J and a trip coil J acting to open the gate end switch G. The trailing cable isi provided with .an

earthed pilot circuit one end of which is shown at K, the other end being assumed to be connected to theea-rthcd fiflsingof the motor or other apparatus. The conductors G .G and G and thexpilot lcircuitare connected at each end by the usual plug and soclt ill or like devices. In the pilot circuit-K 1snn1awiliary winding acting tocon-trol or inod theaction of the primarywvi-nding E Forfinstance, it the earthed pilot circuit K ispopen theefl ect on the secondary wind- 7 ing E may 'be -;arra-nged to have 'sufiicient inductire ettect on the secondary winding E as to (cause the relay Huto operateand open the switch but it the earthed pilot circuit is closed the auxiliary winding 1 then short circuited,may (damp or :moc liify the cli'ect ozt the-primary winding E :and prevent the opening 10% the switch.

lthat we claim zasiou-r invention and desire to secure byuliettei's Patent is:

1.1m an electric pncrtective anrzuigement for :a. trailing cable between an electromagneticallycontrolledswitch and electrical apparatus, the combination with-the earth-ed pilot circuit 0f the cable of an electromagnetic. tripping iderice for the switch ha ing a magnetizing or operating winding.anclta-lso having anauiclliary winding 'cui'tm ith the plot circuit, :such auxiliary winding-heing normally short-circuited :by the pilot circuit for the purpose described.

"2. Ln an electnic protective arrangement for .a three-phase. trailing cable i.l.6t\V.QQ-,I1'ilil1 eleetromagnetically-eontrolled switch and electrical apparatus, the combination with the earthed pilot circuit :of v the cable, ,;of can electromagnetic tripping -.deri ce tor {the switch including an earth-leakage or eo rebalance trzu-istormerthrough which the Three phase conductors :pass from the switch, said vtra nsformcr theing iprovi d ed with three avgindi.ugs,.-a primary w] ding .connectedhetween two of :the phas .a secondary winding; end an auxiliary w nding normally :short cuited by the earthed pilot circuitand-ac g in conjunction-with the secondary wind ng toconztrol the switch. V

In testimony whereof we haaze signed -our names to :this specification.

'H-ENRY' *WILLLAM CLOTHJER.

- WJLLLAM ANTEHONYVTAMBRDSE -YBURVESS.I 

